For hearsay (伝聞), one can append そうです to the plain form of an adjective and verb. For example:
体にいいそうです - Heard it's good for the body
There is also another way to say that and that's using って. For example:
体にいいって - Heard it's good for the body
The question is, what is the difference between these 2 sentences?
「～って。」 is quite casual and colloquial.
いいそうです。 -- polite and formal
いいそうだ。 -- less polite
いいんだって。or いいって。 -- informal, casual, and colloquial
eg
ごま油は、体にいいそうですよ。-- You might say this to your boss, teacher, or customer.
ごま油って、体にいいんだって。-- You might say this to your family or friends.
In addition to Chocolate's answer, it may be worth noting the actual literal difference between the two forms:
「そうです」 means, basically, "it appears to be that way", so 「体にいいそうです」 literally means "It seems that it's good for the body" (the implication being that it seems that way because people have said it's so).
「って」 is a contraction of 「と言う」(see Tae Kim's page), that is, it literally means "(someone) says", so 「体にいいって」 literally translates to "people say it's good for the body" (although depending on context, it might also mean "he/she says it's good for the body", etc, so one needs to be a bit more careful).
